A Smart Choice for Human Cytochromes P450 Phenotyping Assays


Available now!…Silensomes™ Human Liver Microsomes (HLM)


Drug-drug interaction can significantly impact drug safety and efficacy. Prediction of this risk of drug-drug interactions is a requisite in the development of a new drug candidate and the submission of the registration dossier. In vitro identification and measurement of the contribution of the major cytochrome P450 enzymes involved in the human metabolism of a new drug candidate, also called “CYP phenotyping”, helps predict the impact of co-administered drug, or perpetrator, on the pharmacokinetics of the new chemical entity, or the victim. Up until now, these studies are carried out using three common approaches:

  1. Correlation analysis
  2. Antibody or chemical inhibition
  3. Metabolism by recombinant human enzymes

Unfortunately, models such as correlation analysis provide no direct quantitative measurement of the contribution of each CYP in the metabolism of a drug. Models such as recombinant CYP450 enzymes are not fully representative of the liver enzyme profile. Not to mention that many chemical and antibody inhibitors lack sufficient specificity to enable confidence in results

To overcome the disadvantages of the current methodologies, a patented new in vitro drug development model was developed.

Introducing, Silensomes™ HLM

Silensomes™ are validated human pooled liver microsomes (HLMs) chemically and irreversibly inactivated for one specific CYP using mechanism based inhibitors (MBI).

Each Silensomes™ is available as cryopreserved, ready-to-use HLMs chemically knocked-out for one specific CYP activity (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4) with each showing high specificity and efficiency of their targeted CYP inhibition (>80%), and only minor impact (<20%).

The thaw and go format of Silensomes™ enables researchers to focus more on results and less on validating the level of CYP inhibitions.  Silensomes™ are available now from Lonza for compound screening purposes and for regulatory validation.

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Case Study: CYP3A4-Silensomes™ HLM

CYP3A4 activity is specifically and extensively inhibited in CYP3A4-Silensomes™

CYP3A4-Silensomes™ and its homologous control were incubated with different CYPspecific substrates.

Results showed:

  • CYP3A4 mediated metabolism of testosterone, a pure CYP3A4substrate, was totally inhibited.
  • More than 80% of CYP3A4-mediated metabolism of nifedipine and midazolam was inhibited. Residual metabolism of these substrates was inhibited by ketoconazole, revealing the CYP3A5 contribution.
  • There was no impact on the other CYP activities tested.


Catalogue Number Description
SIL200 Human hepatic CYP3A4-Silensomes™
SIL210 Human hepatic CYP1A2-Silensomes™
SIL220 Human hepatic CYP2A6-Silensomes™
SIL230 Human hepatic CYP2B6 Silensomes™
SIL240 Human hepatic CYP2D6-Silensomes™
SIL250 Human hepatic CYP2C8-Silensomes™
SIL260 Human hepatic CYP2C9-Silensomes™
SIL270* Human hepatic CYP2C19-Silensomes™
SIL280* Human hepatic CYP2E1-Silensomes™

Control Silensomes™

Catalogue Number Description
SIL201 Human hepatic Control CYP3A4-Silensomes™
SIL211 Human hepatic Control CYP1A2-Silensomes™
SIL221 Human hepatic Control CYP2A6-Silensomes™
SIL231 Human hepatic Control CYP2B6 Silensomes™
SIL241 Human hepatic Control CYP2D6-Silensomes™
SIL251 Human hepatic Control CYP2C8-Silensomes™
SIL261 Human hepatic Control CYP2C9-Silensomes™
SIL271* Human hepatic CYP2C19-Silensomes™
SIL281* Human hepatic Control CYP2E1-Silensomes™

*Coming soon.

To order Silensomes, contact Customer Service at (800)638-8174 or customerservice-trl@lonza.com.